1. Field of the Invention
The present invention relates to a turbine blade for a gas turbine and particularly to an improvement in an airfoil profile of a first stage turbine blade.
2. Description of the Related Art
A gas turbine of this type that has generally been adopted is configured such that working fluid compressed by a compressor is added with fuel and burned to provide high-temperature and high-pressure working fluid, which drives a turbine. The rotational energy of the turbine thus driven is usually converted into electric energy by a generator coupled to the turbine.
In recent years, more expectations have been placed on improvements in the efficiency of a gas-turbine-and-steam-turbine-combined cycle. It has been intended as one of the means to further increase the temperature and pressure of the working fluid.
As regards a high-temperature turbine component, particularly, a first stage turbine blade, efforts have been made to provide an optimum shape with respect to aerodynamic performance as well as to reinforce a cooling structure in order to deal with increased high-temperature and high-pressure. For example, a shape of a first stage blade in airfoil-profile-height central cross-section is disclosed in a non-patent document, K. Kawaike, et. al.: Integrated CAE System for Cooled Turbine Blade Design and Verification Tests of Analytical Codes: R. J. Goldstein, et. al., Proceedings of International Symposium Heat Transfer in Turbomachinery, Begall House, Inc. 1992.
Incidentally, JP-A-2004-108369 discloses one of the first stage airfoil profiles of a gas turbine blade.